(1) Field of the Invention
The field of the invention is catheters, specifically ablation catheters.
(2) Background of the Invention
Ablation catheters with electrodes are generally known in the surgical art, and ablation electrode catheters with irrigation capabilities are also generally known in the art. Electrode catheters can be used for electrically mapping a body part, or to deliver therapy to a body part, or both.
Using ablation electrodes to create lesions in heart tissues is known for treating heart conditions such as arrhythmia. Linear lesion are known to have some advantages over mere single point lesions. A single point lesion, as its name implies, is created by applying energy at a single point region of tissue. On the other hand, applying energy across an elongated region in a tissue creates a linear lesion.
Creating a linear lesion with only a tip electrode, however, is relatively time-consuming, labor-intensive, and generally impractical. A surgeon may use a typical single point electrode catheter to create linear lesion, by carefully dragging the single point electrode tip across the tissue while applying energy to the tissue surface.
U.S. Pat. No. 5,487,385 discloses a flexible catheter having ring electrodes disposed along its flexible shaft for creating a linear lesion. A surgeon may lay such catheter shaft across a tissue area, and allow the consecutively-arranged ring electrodes to ablate the target tissue using RF energy. The ring electrodes, however, must apply sufficient energy in order to create lesion areas that are connected, thus forming a single linear lesion. Applying too much RF energy, however, can cause unwanted damage. This arrangement often results in a series of spaced-apart single point lesions.
U.S. Pat. No. 6,063,080 discloses a catheter having an elongated electrode. This electrode has micro-slotting or micro-apertures across its surface to improve flexibility of the electrode, thus allowing a surgeon to lay the elongated electrode across a tissue surface.
Despite some desirable properties, such a longitudinal type electrode has several disadvantages. For example, the electrode requires a spherical structure at its tip to prevent the electrode from penetrating tissue. Also, a longitudinal type electrode cannot effectively create a linear lesion when the electrode is laid across a tissue having ridges. Thus, there is a continuing need for new ways to create linear lesions.
All referenced patents, applications and literatures are hereby incorporated by reference in their entirety. Furthermore, where a definition or use of a term in a reference, which is incorporated by reference herein, is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies and the definition of that term in the reference does not apply. The invention may seek to satisfy one or more of the above-mentioned desire. Although the present invention may obviate one or more of the above-mentioned desires, it should be understood that some aspects of the invention might not necessarily obviate them.